Suppose I have a portfolio with securities with different history. Say some securities have 15-20 years of history and some are like Uber or Lyft, which has limited history. There are assets with 1/2/3/5/ etc years of history as well.
How would you go about calculating portfolio Beta? Calculating individual betas for Uber/Lyft etc would be impossible. Hence calculating portfolio beta by taking weighted sum of individual security betas would, in my opinion, be problematic.
I am thinking about creating portfolio value for, say, 10 years, by reassigning weights of securities missing proportionally to other securities. And then calculate portfolio Beta by regressing portfolio returns against the Index returns.
Is that incorrect?
